netem: free skb's in tree on reset

Netem can leak memory because packets get stored in red-black
tree and it is not cleared on reset.

Reported by: Сергеев Сергей <adron@yapic.net>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/sch_netem.c

@@ -358,6 +358,21 @@ static psched_time_t packet_len_2_sched_time(unsigned int len, struct netem_sche
 	return PSCHED_NS2TICKS(ticks);
 }
 
+static void tfifo_reset(struct Qdisc *sch)
+{
+	struct netem_sched_data *q = qdisc_priv(sch);
+	struct rb_node *p;
+
+	while ((p = rb_first(&q->t_root))) {
+		struct sk_buff *skb = netem_rb_to_skb(p);
+
+		rb_erase(p, &q->t_root);
+		skb->next = NULL;
+		skb->prev = NULL;
+		kfree_skb(skb);
+	}
+}
+
 static void tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
 {
 	struct netem_sched_data *q = qdisc_priv(sch);
@@ -610,6 +625,7 @@ static void netem_reset(struct Qdisc *sch)
 	struct netem_sched_data *q = qdisc_priv(sch);
 
 	qdisc_reset_queue(sch);
+	tfifo_reset(sch);
 	if (q->qdisc)
 		qdisc_reset(q->qdisc);
 	qdisc_watchdog_cancel(&q->watchdog);